On April 28, 2025, a significant blackout affected Spain, Portugal, and parts of southwestern France, disrupting daily life for millions and raising questions about the resilience of energy systems heavily reliant on renewable sources.
What Happened?
The blackout began at 12:33 CEST, plunging much of the Iberian Peninsula into darkness for approximately ten hours. Essential services were severely impacted, including transportation, telecommunications, and healthcare. At least seven fatalities were reported in Spain, with one in Portugal, attributed to incidents such as generator failures and fires caused by candles. The economic cost of the outage is estimated between €2.25 billion and €4.5 billion.
At first, some reports pointed to a possible “rare atmospheric phenomenon” as the cause of the blackout. These reports mentioned a statement allegedly from Portugal’s grid operator, REN, suggesting that in extreme weather—like strong storms or intense heat—overhead power lines can start to sway, potentially damaging older or poorly maintained equipment. However, the weather in Spain on the day of the blackout was normal, without any such extreme conditions. The next day, REN denied having made that statement, but didn’t provide any additional explanation about what might have caused the outage
What Caused the Blackout?
The exact cause remains under investigation. Preliminary analyses suggest that the incident was triggered by two fluctuations in the electrical grid, leading to a disconnection of the Iberian system from the broader European grid. This collapse was not directly linked to renewable energy sources.
At the time of the outage, Spain’s electricity mix was approximately 59% solar, 12% wind, 11% nuclear, and 5% gas. Despite concerns about the grid’s stability due to the high share of intermittent renewable sources, experts and officials have stated that the renewable energy share was not unusual and did not directly cause the blackout. The European Union’s energy commissioner and Spain’s environment minister emphasized that the system had operated reliably under similar conditions in the past.
Was Renewable Energy Behind the Blackout ?
While renewable energy sources like solar and wind are variable and do not provide the same grid stability as traditional thermal power plants, the blackout was not solely attributable to their integration. The absence of mechanical inertia in the grid, due to the reduced presence of spinning turbines from fossil fuel and nuclear plants, may have contributed to the system’s vulnerability. However, renewable sources such as solar, wind, and hydro remained operational during and after the event, whereas fossil fuel generation did not.
This incident underscores the importance of enhancing grid infrastructure to accommodate high shares of renewable energy. Investments in energy storage, grid interconnections, and technologies that provide grid stability are crucial to ensure the resilience of future energy systems.
At the time of the blackout, Spain and Portugal were leading the EU in renewable energy use, with around 80% of their electricity coming from solar and wind. Some observers suggested that the high levels of renewable energy might have overloaded the grid. This is because solar and wind power are intermittent sources—their output can change quickly depending on the weather, which sometimes causes instability in the system.
However, experts say this likely wasn’t the issue.
Conclusion
The April 2025 blackout in Spain and Portugal highlights the complexities of transitioning to renewable energy sources. While renewable energy was not the direct cause of the outage, the event emphasizes the need for comprehensive planning and investment in grid infrastructure to support a sustainable and reliable energy future.